نتایج جستجو برای: early diagenesis
تعداد نتایج: 687090 فیلتر نتایج به سال:
[1] The paleoceanographic recording fidelity of pelagic sediments is limited by chemical diagenesis and physical mixing (bioturbation and horizontal sediment transport). Diagenesis and bioturbation are relatively well-studied, but the effects of physical sedimentation have been largely ignored. Modeling U series isotopes (e.g., Th) can potentially quantify horizontal sediment movement, but mode...
Abstract Coal balls are carbonate concretions that preserve peat in cellular detail. Despite their importance to paleobotany, the salinity of coal-ball remains controversial. Pennsylvanian coal from Midland and Illinois basins contain echinoderms early high-magnesium calcite cement. Echinoderm skeletons reflect Mg/Ca ratio seawater which they grew. Here we show well-preserved North American mar...
Abstract Calcium isotopes (δ 44/40 Ca) are particularly useful in palaeo‐environmental studies due to the key role of carbonate minerals continental weathering and their formation seawater. The calcium isotope ratio can provide hints on past changes fluxes, environmental shifts, ecological factors alternatively diagenesis rocks. investigation Late Triassic record offers a great opportunity eval...
Measurements of natural cosmogenic Si (t1/2 ~ 140 years) in tropical deltaic sediments demonstrate for the first time that most Si is present in rapidly formed authigenic clays and not biogenic opaline silica (bSi). The burial of bSi in deltaic and continental margin sediments has likely been greatly underestimated because of diagenetic alteration of bSi to clay, little of which dissolves in th...
Ketzer, J. 2002. Diagenesis and Sequence Stratigraphy. an integrated approach to constrain evolution of reservoir quality in sandstones. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 762. 30 pp. Uppsala. ISBN 91-554-5439-9 Diagenesis and sequence stratigraphy have been formally treated as two separate disciplines in s...
Taphonomic processes affecting bone post mortem are important in forensic, archaeological and palaeontological investigations. In this study, the application of tissue microarray (TMA) analysis to a sample of femoral bone specimens from 20 exhumed individuals of known period of burial and age at death is described. TMA allows multiplexing of subsamples, permitting standardized comparative analy...
Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicate...
Sedimentary deposits yielding extraordinarily-preserved fossils (known as Lagerstätten) may provide significant insights into the physiology and environments of ancient plants, particularly when represent their original characteristics with limited diagenetic modifications. To better understand molecular, isotopic, morphological changes during early stages diagenesis, degradation experiments we...
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